Form SS-4

What is Form SS-4?

Form SS-4 is the application for an Employer Identification Number. Every business that has employees or operates as a corporation or partnership needs an EIN. The form collects information about the business entity, its structure, and expected activities. You can apply online, by phone, fax, or mail, though online is fastest with immediate EIN assignment.

When you need an EIN

You need an EIN before hiring your first employee, when incorporating or forming a partnership, when opening a business bank account that requires one, or when taking over an existing business. Sole proprietors without employees can use their Social Security number but often get an EIN anyway to keep business and personal identification separate.

Applying online vs paper

The online application at IRS.gov takes minutes and provides your EIN immediately upon completion. Phone applications also provide same-day EINs. Fax takes about four business days. Mail takes four to six weeks. Given the speed difference, online application makes sense for most situations unless you lack internet access or have an unusual entity type the online system cannot handle.